Follow focus device



Oct. 11, 1938.

Filed June 24. 1935 4 Sheets-Sheet l I45 I21 7 L /2958 4: EL P /0Z ll I52 79 64 a:

INVENTOR ALBERT W. TONDPEAU ATTORNEY Oct. 11, 1938. A, w TQNDREAU 2,133,063

FOLLOW FOCUS DEVICE Filed June 24, 1935 4 Sheets-Sheet 2 ATTORNEY.

1933- A. w. TONDREAU 2,133,063

FOLLOW FOCUS DEVICE Filed June 24, 1935 4 Sheets-Sheet 3 INVENTCR ALBEQT W. TONDPEAU ATTORNEY Oct. 11, 1938. I A. w. TONDREAU 2,133,063

- FOLLOW FOCUS DEVICE I Filed June 24, 1935 4 Sheets-Sheet 4 BY W ATTORNEY Patented 06.11, 1938 PATENT OFFICE FOLLOW FOCUS' nsvrcn Albert W. Tondreau, Hollywood, Calif., assignor to United Research Corporation, Long Island City, N. Y., a corporation of Delaware Application June 24, 1935, Serial No. 28,102

10 Claims.

This invention relates'to motion picture cameras and more particularly to a follow focus device to be used with a motion picture camera enclosed in a sound-proof casing.

With the advent of sound motion pictures, it became necessary to enclose the motion picture camera and its associated parts in a sound-proof housing to eliminate the noise of the moving parts thereof from reaching the recording microphone. This made it extremely diflicult to photograph a running or action shot as there was no convenient means for accurately adjusting the focus of the objective lens and at the same time following the path of the action with a viewfinder from outside of the sound-proof casing.

A second fault that is encountered in making motion pictures with the use of a plurality of lenses of different focal characteristics is that the stereo-parallax that must be compensated for between a follow focus viewfinder and an objective lens varies for each diiferentdens that is used.

Heretofore, the sound-proof casing or blimp hasbeen provided with one or more. doorswhich must be opened in order to permit focusing the main objective lens and/ or for orienting the viewfinder and/or for focusing the viewfinder. This is objectionable, as it is frequently desirable to adjust one or more of these elements while the camera is in operation for the purpose of photographing action in synchronism with sound. It is undesirable to open the sound-proof casing in this case, however, because the noise of the camera may reach an adjacent microphone.

An object of the invention is to focus the camera lens and/or orient the viewfinder while permitting theblimp to remain closed.

This is accomplished by providing a control knob atthe exterior of the blimp, and by providing a driving connection between this control knob and the camera lens and/or the viewfinder for orienting the latter. Preferably, this driving connection is of such a nature that the camera lens is focused simultaneously with the orientablimp partly'broken away to show the arrangement of the follow focus device.

Fig. 4 is a plan sectional view taken on the line 4-4 of Fig. 3.

Fig. 5 is a side elevational view partly in section of the follow focus device.

Fig. 6 is a front view of the lower part of the focus device taken along the line 6--6 of Fig. 3.

Fig. '7 is a sectional view showing the tension adjusting mechanism for the operating cable and is taken along the line 1-1 of Fig. 1.

Fig. 8 is "a sectional view showing the flexible connection between the upper end of the focusing device and the wall of the camera blimp taken along the line 88 of Fig. 1.

Fig. 9 is a section through the levers taken along the line 99 of Fig. 6. I

Fig. 10 is a plan sectional view of the adjustable pointer and is taken along the line iii-Hi of Fig. 5.

Fig. 11 is a plan view showing the arrangement of cams and a cam follower for controlling the position of the viewfinder.

Referring now to Figs. 1, 3, 4, and 6, a standard motion picture camera I is mounted upon a supporting plate 2 provided in a sound-proof casing or blimp generally indicated at 3. A conventional focusing tube I is provided integral with the side of the camera i but is inoperative while the camera is used within the camera blimp 3 in conjunction with the follow focus device. A plurality of objective lenses such as 4, 5, and 6, is provided in the front of the camera i and is mounted on a lens turret 1. Each of these objective lenses has a different focal length. The lens turret I is adapted to be rotated so as to bring any one of the lenses 4, 5, and 6 into the position before the film aperture (not shown). An indexing pin 8' provided on the front face of the camera I is adapted to engage any one of a number of detents such as 9 and ill on the edge of the turretand thus hold a desired objective lens in alignment when photographing.

The blimp 3 is provided with a door ii at its rear edge which is hinged as at i2 to allow access to the rear of the camera i and its associated film magazine l3 for making adjustments. A door it is also provided on the side of the blimp 3 to allow access for threading the camera. The door it is hinged along its lower edge as at i5 and is locked in position by means of a latch iii. The door It has a semi-cylindrical extension I! thereon to accommodate a viewfinder l8 mounted on the side of the camera I.

Referring to Fig. 4, the door it has a pair of windows i9 and 20 placed at its front and rear edge which register with the viewfinder i8. .A window 2| is provided adjacent the photographing lens 5 to allow the lens to view the scene being taken.

The camera supporting plate 2 is mounted upon rubber cushions 22 and 23 of the type whichis disclosed and claimed in the co-pending application of RobertP. Miller, Serial Number 25,622, filed June 8, 1935. Cushions 22 and 23 are secured to the floor 26 of the camera blimp 3 to prevent vibrations produced by the camera from being transmitted to the exterior of the blimp.

A viewfinder if) having a universal focus or a manually adjustable focus is pivotally mounted at iill to a bracket 25 which is removably secured within a dove-tail joint 26 provided on. the front edge of the camera I as shown in Fig. 4. An extension Zl of the bracket 25 extends diagonally across the viewfinder I8 and has a distended end portion 28 which accommodates an elongated slot 29. The slot 29 receives a knurled set screw 30 threaded into the upper surface of the viewfinder l8. When taking wild shots or whenever it is desirable to take pictures without the follow focus device, the viewfinder may be clamped in any desired position by means of the set screw 38. When the follow focus deviceis used, this set screw 38 is either removed or loosened to allow it to move freely along the slot 29 as the viewfinder I8 is rotated about the point MI by the follow focus device. A spring 3i is attached at one end to the viewfinder as at 32 and at the other end to the bracket 25 as at 33 to thus urge the viewfinder I8 towards the camera i.

Referring now to Fig. 1, the bottom of the viewfinder i 8 has a bracket 33 provided thereon in which is threadably mounted an adjustable stop screw 36. Locking nut 35 holds the stop screw 36 in any desired position.

Referring now to Fig. 11, a stop screw 38 is adapted to be engaged by a cam follower 36 which is pivotally mounted at 31 to a hub 38 provided on the lower end of a follow focus housing 39. The cam follower 36 has an arm 40 provided thereon which carries a cam follower wheel 8| attached to the end thereof. The cam follower 36 is adapted to be engaged and moved by any" one of a series of involute shaped cams 82, 43, d8, 85, and 46 each of which is complementary to one of the objective lenses such as 6, 5, and 6.

Referring to Fig. 5, the cams 42-46 inclusive are secured on the end of a shaft 47. The opposite end of the shaft 81 is provided with a knurled knob 88. An indicator plate 89 is provided at the front of the housing 39 adjacent the knob 88 and bears indicia complementary to the various ob- .iective lenses. That is, the line marked 35 would be complementary to a 35 mm. lens; the line 8.9, complementary to a 40 mm. lens, etc. A series of detents 50 corresponding to the indicia provided on the indicator plate 49 is spaced along the bottom edge of the shaft 41 and is adapted to be engaged by a spring-pressed plunger 5I mounted in a projection 52 provided on a rotatable flanged member 52 which is secured to a ring gear 53 by screws 53. The shaft 41 is slidably mounted within the member 52 but is prevented from relative motion by means of a key 58 which moves along a key way 55 provided in the shaft 67. The member 52 is mounted within a pair of ball bearings 58 and 51 which are secured within the hub 38 of the housing 39. Thus it will be seen that by positioning the knob 48,0pposite one of the numbers on the indicator plate 49, a cam that has been especially designed for a lens of the particular focal length indicated will be positioned to control the movement of the cam follower 36 and through it the axial alignment of the viewfinder I8.

Referring now to Fig. 1, the upper part of the housing 39 is secured by means of a flexible joint generally indicated at 58 to the outer wall 59 of the camera blimp 3. A shaft 60 in axial alignment with the upper part of the housing 39 extends through the wall 59 and has secured at its outer end thereof an operating knob ill. The shaft 60 is rotatably mounted within the wall 59 by means of ball bearings 6i and 62 which are provided within a bearing housing 63 attached to the wall 53 by means of screws 68. A shaft 65 co-axial with the shaft 69 is mounted within the wall I62 of an enlarged annular casing M3 provided on the upper end of the housing 39 by means of a pair of ball bearings 66 and 67. The shaft 65 carries at one end a drum 68. The two shafts 68 and 65 are fastened together by means of a flexible joint generally indicated at 69. The joint 69 is formed by providing a disc of rubber 78 between the two flanged ends H and 72 of the shafts 68 and 65. Screws I3, 74, 15, and 16 (Fig. 8) secure the two flanges II and I2 to the rubber disc F8. The screws 13 and I5 are threadably secured within the flange II while the screws 68 and 16 are threadably secured to the flange I2. Enlarged apertures TI and I8 are provided in the flange II adjacent the heads of the screws 73 and I5 to prevent any metallic connection between the two shafts 69 and 65. This construction is also true of the screws 74 and I6 thus preventing any undesirable vibrations created by the camera and its associated mechanism from being transmitted to the exterior of the blimp where it would create objectionable sound' waves.

Referring to Figs.'1 and 7, the drum 68 has a helical groove 89 provided on its outer circumference to receive a cable 88. The cable is passed around a similarly grooved surface 8| of a lower drum 82 (Fig. 5) to secure a driving connection between the two drums, and its ends 83 and 84 are passed through apertures I44 and I 45 in the drum 68 and are secured as at I46 and I4! "within a bell-shaped ratchet member 85 having ratchet teeth 86 provided at its rear end. The teeth 86 are adapted to be engaged by a springpressed pawl 81 (Fig. '7) which is pivotally secured to the wall I88 of the drum 68 by means of a screw 88. The outer end of the ratchet member 85 is provided with a slot 89. A suitable tool such as a screw driver may be employed to rotate the ratchet member 85 and thus increase the tension of the cable 88. The lower drum 82 (Fig. 5) is divided into a pair of end members 98 and 9| which are secured to a central gear 92 by means of bolts 93 and 9 1. The gear 92 has a longitudinal aperture I50 therethrough to allow the cable 88 to pass from one section 98 of the drum 82 to the other section 9|. The drum 82 is rotatably mounted on ball bearings 95 and 96 secured upon a sleeve 91. Sleeve 91 in turn is secured upon a bolt 98 which is passed through the side wall of the housing 39. The gear 92 engages the ring gear 53 provided on the shaft 41. Thus it will be seen that rotation of the knob 6| will effect rotation of the gear 92 and consequently, through the gear 53, the various cams 42-46 inclusive, to rotate the viewfinder I8 about its pivot point.

Referring now to Fig. 6, the gear 92 is also adapted to mesh with and rotate any one of a number of ring gears 99, I08, and IIII secured tothe objective lenses 4, 5, and 6, it being understood that rotation of the objective lenses 4, 5, 6, etc., causes the said lenses to move in and out thus changing their focal lengths. Therefore,,

the rotation of the knob 6I will effect both the lenses and also the stereo-parallax of the viewfinder I9. A circular indicator disc I92 (Fig. 5) is secured to the knob 9| and bears indicia or distance in feet foreach of the objective lenses to indicate the distance in front of the camera at which an objection will be in focus. A series of graduated scales I93, I94, I95, I99, and I91 each complementary to a certain objective lens is provided on the disc I92. An adjustable pointer I99 is provided adjacent the disc I92 to designate the scale that is to be used and the range which is desired.

Referring to Figs. 6 and 9, it will be noted that the follow focus device is adapted to be moved in and out to disengage the gear 92 from one of the ring gears as I99 provided on the objective lens 5. This is accomplished by providing alever.

arrangement I99 on the lower portion thereof connecting the lower part of the follow focus housing 39 with the camera supporting plate 2. A bracket I I9 is secured to the camera supporting plate 2 by means of bolts III, I I2, and has pivotally secured thereto by means of a bolt H3 an L-shaped lever H4. Lever H4 is also pivotally secured to the lower end of the follow focus housing 39 by means of a bolt H5. The other end of the lever I I4 has a screw H9 secured thereto and projecting at right angles. A second lever H1 is also pivotally mounted to the housing 39 by the bolt H5 and has a transverse elongated slot H9 intermediate its end portions which receives the screw H9. The lever II'I may be secured in any desired angular position, within the limits of the slot H9 relative to the angle lever H4 by means of a locking nut I I9. The purpose of the locking nut H9 is to allow the two levers H4 and II! to be adjusted angularly in relation to each other and thus effect an adjustment of the follow focus device toward or away from the camera I and thus insure proper meshing of the gears 92 and I99. The end of the lever H1 is provided with a spring pressed plunger I29 which is adapted to be engaged in either one of two apertures I2I and I22. A knurled handle I23 is provided on the end of-the spring pressed plunger I29 to allow for removal of the plunger by the fingers of the operator. Thus it will be seen that movement of the plunger I29 from the aperture I2I to the aperture I22 will cause the lower end of the follow focus device to move outward away from the camera I and thus disengage the gear 92 from the gear I99 to allow for rotation of the lens turret I. 'Outward movement of the lower end of the follow focus device will cause the upper end to pivot about the flexible joint 59. A link I59 (Fig. 5) is pivotally mounted between the bolts H3 and H5 to the rear of the housing 39.

Referring now to Figs. 1,2, and 8, I will describe the flexible joint 59 for supporting the follow focus device .onto the wall 59 of the camera blimp 3. A circular plate I24 is secured to the wall 59 by means of screws I25 and I29 and has a pair of raised portions I21 and I29 against which is adapted to be secured a resilient ring I29 of rubberor other similar material by means of bolts I52 and I53. A second plate I39 similar to that of I24 is secured to the casing I43 of the housing v 39 by means of screws I3I and I32. The plate I39 has also a pair of raised projections I33 and.

I34 which are adapted to engage the rubber ring I29 at right angles to the projections I21 and I29 on the plate I24. The rubber ring I29 is secured to the projections I33 and I34 by means of bolts I35 and I39. Thus it will be seen that metallic connection between the member 39 and the wall 59 of the camera blimp is prevented to insulate any vibrations created by the camera 'and its associated mechanism from being transmitted to which is secured within annular openings I39 and I39 provided in the plates I24 and I39.

In the operation of this device, the plunger I29 (Fig. 6) of the lever H1 is moved to engage the aperture I22 to thus disengage the gear 92 from the gear I99 of the objective lens 5. The lem turret I is then rotated until a desired lens is brought into position in front of the photographing aperture and the lens barrel is rotated until the lens is set for infinity. The pointer I 99 is then adjusted to a position where it will read along a scale on the indicator disc I92 which is complementary to the photographing lens being used by releasing a clamp screw I (Figf 10) which allows the pointer I99 to slide up or down in a guide block I59 secured to the wall 59 of the blimp as by screws I5'I. The knob 9i is then rotated until the scale also reads infinity. The plunger I29 is then returned to its normal position at which time it engages the aperture I2I to allow the teeth of the gear 92 to mesh with the teeth of the ring gear provided on the desired lens. The viewfinder I9 is then manually moved outward against the action of the spring 3I (Fig. 4) to allow the knob 49 provided on the end of the shaft 41 (Fig. 5) to be moved along the scale 49 to a position opposite the number corresponding to the focal length of the particular lens being used. Referring to Fig. 11, the cam follower 39 has a spring I59 attached thereto as at I51, the other end being attached as at I59 to the housing 39. On manual movement of the viewfinder I8 outwardly away from the camera I, the spring I59 also moves the cam follower 39 outward to clear the cam follower wheel H from the cams 42 to 49 inclusive until the desired cam is placed in position. In this position, one of the cams 42, 43, 44, 45, or 49 corresponding to the particular photographing lens being used will then be positioned opposite the cam follower 39. Thus it will be seen that by rotating the knob 9I so that the pointer I 99 indicates the distance in feet commensurate with the distance of the object being photographed from the objective lens of the camera that movement will be transmitted to the gear 92 (Fig. 5) which will advance or retract the lens barrel 5, through engagement with the ring gear I99, to keep the objective lens properly in focus and at the same time rotate the gear 53 and consequently the cams "-49 inclusive to pivot the viewfinder about the point MI and thus keep it in correct alignment with the object being photographed.

Having thus described the invention, whatis claimed as new and desired to secure by Letters Patent, is:

1) View finder apparatus for a motion picture camera comprising a lens turret for said camera adapted to support a plurality of diflerent objective lenses, means for mounting a plurality of cams corresponding in number to said objective lenses, a follower mounted adjacent said cams and adaptedto engage with a selected one of said cams, means for selecting a certain cam for engagement with said follower, a view finder contacting said follower and adapted to be moved by said follower, and means interconnecting said cams and a selected objective lens for simultane-- ously focusing said selected objective lens and for rotating said cams.

2. View finder apparatus for a motion picture camera comprising a lens turret for said camera adapted to support a plurality of different objective lenses, a finder, means for pivotally supporting said finder adjacent said camera, means including a plurality of rotatable cams interposed between said'camera and said finder for laterally shifting the axis of said finder in coordination with the focusing movement of each of said objective lenses, means for selecting a cam for a particular objective lens, and means for interconnecting said cams and a selected lens for simultaneous movement thereof.

3. View finder apparatus for a motion picture camera having a lens tube provided with a ring gear, said apparatus comprising a view finder adapted to have its optical axis shifted in a substantially horizontal plane, a support, a drive gear and a second gear continually in mesh with said drive gear mounted in said support, means under control ofv the rotation of said second gear for laterally shifting the axis of said view finder, means formounting said support for pivotal movement with respect to said camera to mesh and unmesh said drive gear with relation to said ring gear, and means for operating said drive gear from a remote point.

4. In combination, a motion picture 'camera having a photographing aperture, a plurality of objective lenses of different characteristics mounted adjacent said aperture, means for selectively positioning one of said lenses in front of said aperture, a view finder pivotally mounted adjacent said aperture, means for selectively controlling the alignment of said View finder to correspond to the field of view of a predetermined objective lens, a sound-proof casing for said camera, means adjacent the outside of said soundproof casing for remotely controlling said lastmentioned means, and means for insulating said last-mentioned means from said sound-proof casmg.

5. In combination, a motion picture camera having a plurality of photographing lenses of different characteristics, a universal focus view finder pivotally mounted adjacent said camera,

means exclusive to each of said photographing lenses for controlling the axial alignment of said view finder to correspond to the field of view of each of said photographing lenses, a sound-proof casing for said camera and said view finder, a

pair of windows in said sound-proof casing in axial alignment with said view finder, and means adjacent said sound-proof casing for remotely controlling the focus of a pre-selected photographing lens and the corresponding axial alignment of said view finder, said means being resiliently mounted on said casing.

6. The combination of a motion picture camera having a plurality of photographing lenses of different focal characteristics, a universal focus view aisaoee pair of windows in said sound-proof casing in axial alignment with said View finder, and means adjacent said sound-proof casing for remotely controlling said focusing means of said objective lens, said means being insulated against vibration from said casing and said focusing means.

'7. In a motion picture soundproof camera, the combination of a motion picture camera, a sound-= proof casing surrounding said camera, a View finder positioned adjacent said camera, means interposed between said view finder and said camera for adjusting the angular relationship between the axis of said view finder and the axis of said camera, said means including a plurality of cams having different shapes, a plurality of objective lenses for said camera, means for interconnecting each of said lenses with a cam of a particular shape, an adjustable belt means for interconnecting said last mentioned means with a control means, -a portion of said control means extending exteriorly of said soundproof casing,

and means for resiliently' connecting the portion of said means extending without said casing and said control means within said casing to prevent vibrations of said camera from being transmitted without said casing.

8. Viewfinder apparatus for a motion picture camera having a lens tube provided with a ring gear, said apparatus comprising a viewfinder adapted to have its optical axis shifted ina substantially horizontal plane, a support, a drive gear and a second gear mounted in said support, means under control of the rotation of said second gear for laterally shifting the axis of said viewfinder, means for mounting said support for movement with respect to said camera to mesh and unmesh said drive gear with relation to said ring gear, while leaving said drive gear in mesh with said second gear, and means for operating said drive gear. I

9. Camera operating mechanism comprising the combination of a casing having a rigid wall and a lining 'of sound deadening material therefor, an aperture in said wall and in said material, a bearing fixed to said wall and mounted in said aperture, a shaft in said bearing, a handle outside of said wall on said shaft, a stub shaft, resilient coupling between said first mentioned shaft and said stub shaft, a bearing for said stub shaft, a housing for said last mentioned bearing, means for resiliently supporting said housing from said wall, and camera mechanism under control of said stub shaft.

10. The combination of a camera, a viewfinder pivotally mounted thereon, a bearing, a speed control shaft slidably and rotatably mounted in said bearing, a gear keyed to said shaft for rotating the same, a hand operating device for rotating said gear, a plurality of different shaped cams on said shaft, a cam follower adapted to selectively engage said cams and connected to said viewfinder for pivotally moving the same to change the angle between the axis of the camera and the axis of the view finder, said shaft being slidable along its axis to select a desired cam and being rotatable about its axis to rotate said cams and means co-operating with said shaft for selectively locking the same in positionsto hold a selected one of said cams in engagement with said cam follower.

ALBERT W. TONDREAU. 

